1. Field of the Invention
This invention relates to air bag devices for automobiles whereby air bags can be entirely mechanically started.
More particularly, the invention relates to an air bag device wherein an opening part of a pressure gas container provided with an opening communicating with an air bag is tightly sealed with a frangible inner lid.
2. Description of Relevant Art
There is already known an air bag device for automobiles which detects the magnitude of an impact at the time of a collision of an automobile to start a gas generator in case the detected value is larger than a set value, to thereby inflate an air bag. The inflated air bag will reduce the impact to which the occupants are subjected, and the device will thus increase the safety of the automobile. Such an air bag device comprises an air bag, a gas generator, gas generation starting means, and impact detecting means.
Such known air bag device is generally of an electric fuse type which has many components and much wiring. The wiring and installation must be made very carefully and the cost is high. In addition, wiring breaks and circuit trouble are likely to occur at the time of a collision. Thus, there is also a problem in reliability.
Therefore, in an air bag device it is required that the device for starting the air bag should be activated at the time of a collision, and should have a structure as simple as possible. It should also have few parts, should be low in cost, should detect an impact, and should operate very quickly on the basis of a detected result. Also, it should inflate the air bag, should be positive in operation, should operate under any conditions, should be high in reliability, and should be able to be easily installed in an automobile by being assembled as a unit without requiring many pipings and wirings.
It is also preferable that the device be entirely mechanical while guaranteeing positive operation. It is also desirable that circuit trouble such as is caused by a long waiting period as in an electric type will not occur. There should be no delay and failure of the operation by the failure of the ignition due to hygroscopicity as in a type using a powder. There should be no need for inspection, replacement, and service of an impact detecting and transmitting system for preventing such delay and failure of operation.
It is also preferable that the gas generator should be so close that the operation of the detecting means may be transmitted directly to it to start the device.
It is also preferable that the device fitting space in the automobile should be as small as possible with respect to other mechanisms and parts. If there are many parts and pipes and wiring are required, a large space will be required. If the entire device including the piping and wiring fitting means and starting means is made large, it will not be easy to obtain the fitting space. It should not be necessary to alter the structure of the car body and to move and modify the instruments in the fitting, piping and wiring parts. Therefore, it is preferable to make the device small.